In manufacturing plants bulk material is transported using various different techniques. The material may be transported used using front end loaders, physical labor, conveyors, lifts, bucket elevators or pipes. One transportation approach that is in widespread use is to transport the material on slightly inclined duct of fluidized air referred herein as an air slide.
An air slide is a system that uses the forces of gravity to move the material. Air slides (also known as Aeration conveyors) are used to gravity-convey powders by passing low-pressure air through a porous membrane media into the bed of the material being handled, resulting in the material becoming fluidized. Material movement is achieved by sloping the air slide to match the fluidized angle of repose of the material. At the correct slope, fluidized material will “flow” with the consistency of a liquid.
Typically air slides are used to transport material that generally has a granular consistency of flour, or powder. Examples of material that are transported by air slide are raw meal, and finished cement in cement plant operations. In many industries, it is beneficial to have measurements of the physical properties and composition of the material being transported. This information is used for various reasons, including verifying that the material is the correct blend or mixture of material, or that the material is has the correct material properties, or to use the measurements for optimizing the manufacturing process. Different measurements can be taken, including the elemental composition of the material, the molecular composition of the material, the granular size of the material, the reflectance of the material, the density of the material, and so forth. The exact measurements depend on the requirements for the application.
Various systems in the prior art have been developed to address quasi-real time assessment of moving material, primarily for non-air slide systems. For example, an in-line analyzer that is in wide spread use is a conveyor-belt analyzer using a technology called Prompt Gamma Neutron Activation Analysis (PGNAA). PGNAA uses thermal neutrons to measure the elemental composition of material on a conveyor belt. However, these systems work on conveyor belts and do not work on air slides. This is because both the low density of the material and the air slide geometrical differences render current technology unfavorable. An approach used on air slides is Near Infra-Red (NIR), but this is a surface measurement and this measurement is not accurate because of inaccuracies due to changing characteristics of the material and layering in the material. To date, there is no highly accurate system for measurement of fluidized material in an air slide.
Therefore, there has been a long-standing need in the industry for accurate, higher-performing air slide analyzers. Various details of such analyzers are elucidated in the following description.